Polyolefin compositions and laminated article

ABSTRACT

Blends of propylene polymer, ethylene-vinyl acetate copolymer and optionally a synthetic rubber, with small amounts of a polyterpene resin as a compatabilizer, possess excellent properties for the manufacture of heat-sealable and sterilizable films as well as for the manufacture of molded speciality sealed containers and bottles.

This is a division of application Ser. No. 812,582, filed Dec. 23, 1985.

FIELD OF THE INVENTION

The present invention relates to novel polyolefin compositions havingremarkable strength and toughness properties, and in particular toblends of a propylene polymer, an ethylene-vinyl acetate polymer, aspecific compatabilizer and a synthetic rubber as an optional component.

One aspect of the invention relates to resin compositions useful e.g. inthe manufacture of strong and flexible parenteral solution bag filmswhich are heat sealable and sterilizable.

A further aspect relates to resin compositions suitable for themanufacture of squeeze bottles and containers.

Still another aspect relates to compositions which have a high tearresistance and are useful e.g. in the manufacture of containers and ofseals for so-called "tear tab" containers. Other aspects of theinvention relate to monolayer and coextruded films suitable formanufacture of IV bags.

BACKGROUND OF THE INVENTION

Parenteral solutions broadly cover fluid replacement, electrolytereplacement and are vehicles for drug medication. Solutions includeblood plasma, platelets, red cells, kidney dialysis solutions, salinesolutions and nutritional products. These solutions were initiallybottled in glass, however, with the introduction of the collapsibleparenteral solution bag some years ago, airborne contamination wassignificantly reduced since the flexible bags empty without outside airentering the system.

The general requirements of a resin used in the manufacture of theparenteral solution bags include flexibility, clarity, toughness at lowtemperatures, heat-sealability, good processability, moisture vaporpermeability resistance and ability to be sterilized. The industry ispresently employing a highly plasticized PVC film for this purpose.Although this resin does meet most of the requirements, a material ispreferred that has little or no plasticizer. Also, the PVC film is notvery resistant to moisture vapor permeability, and consequently, thecontinuing loss of moisture of the parenteral solutions reduces theirstorage life considerably. Therefore, it is required that the bag besealed within an overpouch made from a film resin designed to have a lowwater vapor transmission rate (WVTR).

In the manufacture of molded specialty bottles and containers, many ofthe above-mentioned properties are also desired although otherproperties might need to be different e.g. the degree of stiffness mightbe varied from one application to another.

It is therefore an object of the present invention to provide a resincomposition which is adapted for processing into heat-sterilizable,flexible films.

It is another object of the invention to provide a resin compositionadaptable for the manufacture of flexible containers.

It is a further object to provide a composition useful in themanufacture of tear tab bottles.

It is an object of the present invention to provide a film useful in themanufacture of sterilizable, collapsible bags for direct and forindirect containment of parenteral solutions.

THE INVENTION

In accordance with the present invention there is provided polymercomposition comprosed of:

(a) from about 10 to about 98 wt % of a propylene polymer;

(b) from about 1 to about 50 wt % of an ethylene vinyl acetatecopolymer;

(c) from about 0 to about 50 wt % of a synthetic rubber, and

(d) from about 0.005 to about 1.5 wt % based on the total weight of (a),(b) and (c) of a polyterpene resin.

The propylene polymer resin component can be a propylene homopolymer, arandom copolymer of propylene and ethylene containing from about 0.5 toabout 6 wt % polymerized ethylene and preferably from about 1 to about 5wt % of polymerized ethylene, or a mixture of the homopolymer andcopolymer.

The ethylene-vinyl acetate copolymer should be a high molecular weightresin containing from about 3 to about 25 wt % polymerized vinyl acetategroups preferably between about 4 and about 12 wt %.

The synthetic rubber component, if present, is suitably selected frombutyl rubber, polybutadiene, polyisobutene, styrene-butadiene rubber,ethylene-propylene rubber, EPDM, etc.

The polyterpene resin compatabilizer is a thermoplastic polymer producedby the polymerization of terpene hydrocarbons consisting primarily ofeither beta-pinene and dipentene. These resins are commerciallyavailable and have heretofore been used as tackifiers and adhesivepromoters.

For heat sterilizable film applications the preferred composition is ablend comprising:

(a) from about 10 to about 50 wt % of the propylene polymer;

(b) from about 10 to about 60 wt % of the ethylene-vinyl acetatecopolymer;

(c) from about 10 to about 60 wt % of the synthetic rubber, and

(d) from about 0.01 to about 1.5 wt % based on the total weight of (a),(b) and (c) of the polyterpene resin.

The most preferred ranges for the four components are respectively:

(a) from about 15 to about 35 wt %;

(b) from about 30 to about 50 wt %;

(c) from about 30 to about 50 wt %, and

(d) from about 0.1 to about 1 wt %.

One optional component of the resin blend is an agent added in aquantity effective to produce films of improved clarity. Examples ofsuitable agents are sodium benzoate, dibenzylidene sorbitol, sorbitanmonooleate and others. Usually the agents are added in quantitiesbetween about 0.1 and about 2 wt % based on the total weight ofcomponents (a) through (c).

The blend composition of the present invention is easily processableinto blown or cast film products which, in addition to high clarity,exhibit other desirable properties such as flexibility, toughness at lowtemperatures, heat-sealability. Also, the films have good resistance tomoisture vapor permeability and can be steam sterilized at 121° C.without significantly affecting its physical properties in a detrimentalway. Finally, the films contain no additives, which would prevent theiruse in food or medical applications, either in direct or indirectcontact.

The film should have a thickness usually in the range from about 3 toabout 10 mils for the manufacture of collapsible, flexible parenteralsolution bags.

In order to improve the read-through clarity of the film prepared fromthe above resin blend, it is sometimes preferable to coextrude the resinwith a propylene polymer, such as the propylene polymer component (a) ofthe present invention to produce a composite film of at least twolayers. A three-layered film structure with propylene polymer outerlayers is within the scope of the invention. For best heat-sealabilityit is preferred that a two-layered composite be employed in themanufacture of IV bags with the propylene polymer as the outside filmlayers.

The same resin blend is also useful in the manufacture of flexiblecontainers such as squeeze bottles or tubes. The bottles or tubes can beinjection molded or blow molded using any conventional techniques andcan be used for containment and dispersion a variety of viscousmaterials such as salves, ointments and lotions. Foods and condimentsare also packaged with advantage in the squeeze containers.

Another embodiment of the present invention relates to resins useful inthe manufacture of more rigid bottles and containers having improvedtear resistance. Specifically, these resins are particularly desirablefor the manufacture of tear tab containers. i.e. containers which areformed, filled and sealed in one manufacturing operation. The seals ofthe filled containers are broken by manual pulling on the tear tabthereby releasing the container top from the container. It is of realimportance that there should be no failures such as breaking, splitting,etc. of the tear tab during the opening of the container.

The preferred resin composition of improved tear resistance is comprisedof:

(a) from about 90 to about 99 wt % of the propylene polymer;

(b) from about 1 to about 10 wt % of the ethylene-vinyl acetatecopolymer;

(c) from about 0 to about 9 wt % of the synthetic rubber; and

(d) from about 0.005 to about 1.5 wt % based on the total weight of (a),(b) and (c) of the polyterpene resin.

The most preferred ranges for the four components are respectively:

(a) from about 92 to about 98 wt %;

(b) from about 1.5 to about 7 wt %;

(c) from about 1.5 to about 7 wt %; and

(d) from about 0.01 to about 1.0 wt %.

The present invention is further described in more detail by way ofexamples, which are provided for illustration, but it is not intended tobe limited thereby.

EXAMPLE 1

A blend was prepared of 40 pounds Polysar butyl rubber XC 961, 40 poundsof and ethylene/vinyl acetate copolymer (containing about 9.0 wt % vinylacetate groups), 20 pounds of a random copolymer of propylene andethylene (containing about 2.3 wt % ethylene groups) and 0.5 pounds ofZonarez 7115, a polyterpene resin based primarily on dipentene. Theblend was used in preparing a blown film of 7 mil thickness. It hadexcellent toughness, was easily heat-sealable and was flexible. Pouchesmade from these films were filled with water, heat-sealed and tossed inthe air to simulate a 10 foot drop. All pouches survived at least 6drops at ambient temperature.

EXAMPLE 2

The resin blend of Example 1 was coextruded with the randompropylene/ethylene copolymer component into an 8 mil three-layered filmcomposite with the random copolymer as the outside layers.

Table 1 lists the physical properties of the film which also hadexcellent see-through properties.

                  TABLE 1                                                         ______________________________________                                                       Machine         Transverse                                                    Direction       Direction                                      ______________________________________                                        Tensile @ Yield, psi                                                                           1230              790                                        Tensile @ Break, psi                                                                           2570              1330                                       Elongation @ Break, %                                                                           600              570                                        1% Secant Modulus, psi                                                                         20600             12100                                      Dart Drop (Method A), gms >1600.sup.1                                         Haze, %                   25.0                                                Gloss @ 60°, %     44                                                  Yellowness Index           1.5                                                (Transmission)                                                                ______________________________________                                         .sup.1 No breaks were obtained at maximum weight.                        

EXAMPLES 3-5

Three resin blends suitable for tear tab bottle production were preparedfrom the components of Example 1 in the proportions listed in Table 2,which also shows the results of test performed on the compositions.

                  TABLE 2                                                         ______________________________________                                        Example        3         4         5                                          ______________________________________                                        Propylene Random                                                                             95.0      96.87     93.75                                      Copolymer - lbs                                                               Ethylene/Vinyl 4.5       1.56      3.12                                       Acetate - lbs                                                                 Butyl Rubber - lbs                                                                           --        1.56      3.12                                       Polyterpene - lbs                                                                            0.5        0.015    0.03                                       Flexural Modulus, kpsi                                                                       125       129       127                                        Tensile @ Yield, psi                                                                         3770      3870      3700                                       Tensile @ Break, psi                                                                         --        --        --                                         Elongation @ Break, %                                                                        >700      >700      >700                                       HDT @ 66 psi, °C.                                                                      85        87        86                                        Izod, ft-lbs/in                                                                              2.2       1.8       2.3                                        Panel Tear Test                                                               (ASTM-D 1938)                                                                 Panel Thickness,                                                                             0.024-0.032                                                                             0.024-0.032                                                                             0.022-0.030                                range in inches                                                               Initial force - lbs                                                                          3.4       3.6       3.2                                        Maximum Force - lbs                                                                          17.0      20.5      18.0                                       ______________________________________                                    

No failures were observed in tests opening sealed bottles by pulling thetear tabs.

It is to be understood that many modifications and alterations can bemade to this invention without departing from its scope, which isdefined by the specification and appended claims.

What is claimed is:
 1. A composite film comprising a first layerproduced from a resin comprised of:(a) from about 10 to about 50 wt % ofa propylene polymer selected from the group consisting of propylenehomopolymer, a random copolymer of propylene and ethylene containingfrom about 0.5 to about 6 wt % polymerized ethylene, or a mixture ofsaid homopolymer or copolymer; (b) from about 10 to about 60 wt % of anethylene-vinyl acetate copolymer; (c) from about 10 to about 60 wt % ofa synthetic rubber; and (d) from about 0.01 to about 1.5 wt % based onthe total weight of (a), (b) and (c) of a polyterpene resin,and a secondlayer conextruded with the first layer and comprised of the propylenepolymer of component (a).
 2. The composite film of claim 1 whereincomponent (a) ranges from about 15 to about 35 wt %; component (b) fromabout 30 to about 50 wt %; component (c) from about 30 to about 50 wt %and component (d) from about 0.1 to about 1 wt %.
 3. The composite filmof claim 2 further comprising a third layer of the resin of component(a) coextruded with the first and second layers and positioned toenclose the first layer between said second and third layers.
 4. Thecomposite film of claim 1 further comprising a third layer of the resinof component (a) coextruded with the first and second layers andpositioned to enclose the first layer between said second and thirdlayers.